A MassINC Polling Group survey found if the election were held today, 38 percent of registered voters would cast their ballot for Brown, while 40 percent would cast their vote for Warren, a Harvard professor and consumer advocate. Sixteen percent were undecided.

Because this was a poll of registered voters, as opposed to likely voters, the undecided number is probably higher than the actual number of voters who haven’t yet made up their mind in the white-hot race which could decide control of the Senate.

Both Brown and Warren are seen favorably by Massachusetts voters. Fifty percent of those polled see Brown favorably, while 33 percent have an unfavorable view of him. Forty-seven percent of those polled see Warren favorably, while 27 percent have an unfavorable opinion of her.

MassINC polled 503 Bay State residents, of whom 445 were registered voters, by live telephone interview to landlines and cellphones in English and Spanish. The poll was in the field July 19-22. The results from registered voters are reflected above. The margin of error among those voters was 4.7 points.